In an electrophotographic device for which plain paper is used as recording paper, a copy is generally made through the following steps. First, the surface of an image carrier is charged electrostatically by a discharge and then an image is illuminated to be projected on the surface of the carrier, so that an electrostatic latent image is formed. Next, charged toner is adhered on the electrostatic latent image and thus a toner image is developed. The toner image is transferred to recording paper and lastly, the recording paper with the toner image transferred thereto is heated and pressurized so as to fix the toner on the recording paper.
Accordingly, in order for an electrophotographic device to sequentially print on a plurality of pieces of paper, the residual toner on the surface of the image carrier needs to be removed after the toner image has been transferred from the image carrier to the recording paper in the above step. Such residual toner is generally removed by a cleaning blade for an electrophotographic device. A cleaning blade for an electrophotographic device is generally formed of a supporting member made of a metal plate, an elastic rubber member, and an adhesive layer for joining the supporting member and the elastic rubber member together.
Since electrophotographic devices have been recently required to produce printed materials of a higher level of quality, polymerized toner having a more spherical (perfectly spherical or irregularly shaped) particle shape and a smaller particle diameter than conventional pulverized toner has come to be used. Polymerized toner particles of this kind easily roll, and thus the residual toner particles may pass under the blade, which may result in cleaning failure.
In order to solve the above problem, a conventional cleaning blade that has an elastic rubber member with high hardness and high rebound resilience can be used since it has an advantage in the cleaning ability; however, such a cleaning blade has a short life span because of its poor abrasion resistance (durability), and therefore the blade needs to be changed frequently. In the case where a cleaning blade designed to maintain the abrasion resistance of the blade is used, on the other hand, the cleaning ability (the cleaning ability particularly under low-temperature and low-humidity conditions) are decreased. That is, in the case where polymerized toner is used, it is very difficult to achieve both sufficient abrasion resistance and sufficient cleaning ability with the conventional techniques.
Patent Document 1 discloses a cleaning blade having a double layer structure with an area to come into contact with a photoreceptor and an area not to come into contact with the photoreceptor. Here, the area to come into contact with the photoreceptor has high rebound resilience (30 to 70%) and the area not to come into contact with the photoreceptor has low rebound resilience (5 to 40%). Patent Documents 2 and 3 each disclose a cleaning blade for an electrophotographic device which includes a supporting member and an elastic rubber member that has a double layer structure with an edge layer and a base layer, each of the layers having specific hardness and rebound resilience.
However, the hardness and rebound resilience of the respective edge layer and base layer of those cleaning blades have not been studied in detail. Further, the cleaning blades disclosed therein might not be able to achieve both sufficient abrasion resistance (durability) and sufficient cleaning ability (particularly under low-temperature and low-humidity conditions).    Patent Document 1: JP 2003-29594 A    Patent Document 2: JP 2002-214989 A    Patent Document 3: JP 2002-214990 A